At a Loss for Words? This site can help:

Losing a loved one can be difficult . . . because other people may not know what to say to you without sounding dumb.  But now there’s a website that  gives advice on how you can express the right level of sensitivity while writing a sympathy note or offering condolences.  It offers tips in special situations like a friend just diagnosed with cancer, someone who loses an estranged parent, or writing a sympathy note when you never met the deceased person.  Here's the site: WordsThatComfort.com